Fossil fuels remain the main source of energy, particularly in the transportation industry. However, due to the large CO2 production associated with fossil fuel use, it is also a major contributor to global warming.
Among these fossil fuels, liquid fuels are being widely used in the transportation industry because of their safety and high calorific values. Liquid fuels still produce large amounts of CO2, and in order to capture the CO2, different techniques are currently available including pre-combustion, post-combustion, and oxyfuel combustion technologies. Currently, oxyfuel combustion technologies are considered some of the most promising carbon capture technologies. For oxyfuel combustion, oxygen is burnt in a combustion chamber with fuel and the combustion products include only CO2 and H2O. The CO2 and H2O can then be separated via a condensation process leaving behind only CO2 that can be recycled or stored through the sequestration process. This process requires pure oxygen (O2), obtained via cryogenic distillation for example. However the cryogenic distillation process of separation of O2 from the air is very costly.
One of the alternatives for the separation of O2 from air that may be more cost effective is the use of Ion Transport Membranes (ITMs), which can reduce the penalty of air separation units in oxy-combustion. These ITMs have the capability of separating the O2 from air at elevated temperatures, typically above 700° C. Oxygen permeation through these membranes is a function of partial pressure of oxygen across the membranes, membrane thickness, and the temperature at which these membranes are operating. When the combustion is done simultaneously with the O2 separation via ITMs, the unit is generally referred to as an oxygen transport reactor.
One of the main challenges of oxygen transport reactors is the low fluxes that are obtained by the membranes. Under these low fluxes the heat rates generated in a given volume is relatively low.
As such, there is a need for an oxygen transport reactor that addresses the deficiencies of the prior art, namely the low fluxes obtained by the membranes and consequently the issue of heating up the membranes economically.